Continuity mistake: In the scene where Lionel Hutz hands over the $106 check, Abe Simpson's room number is 18. After Abe called Homer, the manager of the Retirement Castle comes in. The number 18 has now disappeared.
22 Short Films About Springfield - S7-E21
Continuity mistake: When Skinner and the superintendant are having lunch, Skinner brings in four burgers. The superintendant takes one, and suddenly there is only one left.
Continuity mistake: When Homer is shouting at Skinner about losing Bart, if you look closely you can see that the box with the red cap goes past Homer. However, when he turns round and sees that red cap on a box, that box has already gone by.
Revealing mistake: When we see people digging Bobo out of the ice, they put him in a bag. If you look carefully you can see another Bobo put in another bag just before the shot changes.
Audio problem: When Homer is talking to the family about their complaints about the nerds, he says something that ends in "where we can all live in harmony". When he says this the audio does not match his mouth movements.
Tree House of Horror VII - S8-E1
Continuity mistake: In 'The Genesis Tub,' when Skinner is grading the universe in the tub, his clipboard changes from brown to blue. (00:17:55)
Two Cars in Every Garage and Three Eyes on Every Fish - S2-E4
Continuity mistake: After the safety expedition has taken place, we see that when everyone is in Burns' office that by his main doors there are 4 buttons on the wall. Yet when a shot from further away is shown, they are not there.
The Great Money Caper - S12-E7
Continuity mistake: When they are driving home Marge starts to moan at the children to quiet down. In this shot she has no lipstick. In the next shot from outside the car she has lipstick on and has it for the rest of the scene.
The Trouble With Trillions - S9-E20
Continuity mistake: In the scene where Homer is eating a hot dog just before the post office closes for the day, the vendor behind the hot dog cart has a apron over his shirt. The very next shot the apron has disappeared. (00:05:05)
The Springfield Files - S8-E10
Continuity mistake: When the 'alien' is seen on the news, it is shown on the film Bart made coming out of the trees, but earlier on, when the alien came out of the woods, Bart is seen not holding the video camera.
Continuity mistake: At the end of the episode, Homer puts twenty dollars into Moe's tips jar, but in the next shot the twenty-dollar note has disappeared. (00:20:40)
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Continuity mistake: During the song "Its the American Way" Snake is robbing Hans Moleman during Chief Wiggum singing and Snake's hair is blue. His hair has always been a brown-red color. In the very next scene to confirm its a mistake you see him in the park saying "Yo Sherry Bobbins" and his hair is back to its brown-red color.
Continuity mistake: When the flashback of Ned and Todd Flanders singing in the Simpsons' doorway, Homer says he could use a TV tray. Then it goes back to the present time and Homer picks up a beer from the TV tray which is next to the couch. The TV tray was never there at any other point in the show. (00:10:40)
The Secret War of Lisa Simpson - S8-E25
Continuity mistake: When Lisa and Bart are practising for the 'Eliminator', Lisa doesn't have a rope round her waist, but when she falls she does.
Lisa on Ice - S6-E8
Continuity mistake: When Lisa throws her academic alert into the trash, she jumps half way across the stage without taking a step.
Much Apu About Nothing - S7-E23
Continuity mistake: When Homer comes home with Apu, Lisa closes the book she's reading and slides it to the side on the sofa. When she stands in the next shot,the book has gone.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Revealing mistake: When Dr Hibbert is examining Marge's hairs (and I think another time in the episode), some holes are too low and you can see through her head.
I, (Annoyed Grunt)-bot - S15-E9
Continuity mistake: The jagged piece of metal that Homer pulls from his arm disappears from the bedside table in the very next shot. (00:16:30)
Other mistake: When Marge sees the letter from Homer, she says "You won't see me again until I'm a man." On the paper though, it reads 'But you will not see me-' and the sentence is cut off, and the rest of the paper is blank. (00:16:10)
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.